Exam 2 Part three Flashcards Preview

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Flashcards in Exam 2 Part three Deck (111):
1

Type of muscle fiber that fatigues easily

Fast fiber

2

Muscle fiber plasma membrane

Sarcolemma

3

Muscle whose function opposes agonist

Antagonist

4

Connective tissue covering a fascicle (skeletal muscle fascicle)

Perimysium

5

Functional contractile unit of a skeletal muscle fiber

Sarcomere

6

Protein in thick filaments

Myosin

7

Sarcomere region with thin filaments only

I band

8

Muscle that surrounds an opening

Circular muscle

9

The resting tension within a muscle

Muscle tone

10

The more mobile attachment of a muscle

Insertion

11

The unit of muscle structure that is composed of bundles of myofibrils, enclosed within a sarcolemma, & surrounded by a connective tissue covering called endomysium is a?

Muscle fiber

12

During the contraction of a muscle fiber, myofibrils...

Shorten

13

In a convergent muscle, the fibers are?

Widespread over a broad area & joined at a common attachment site

14

The plasma membrane of a skeletal muscle fiber is called the

Sarcolemma

15

In a skeletal muscle fiber a triad is composed of?

One transverse tubule & two terminal cisternae

16

During development, the ____ of a somite gives rise to the skeletal muscle

Myotome

17

What is a synapitc knob?

Expanded tip of an axon at the neuromuscular junction

18

The bundle of dense regular connective tissue that attaches a skeletal muscle to bone is called a(n)

Tendon

19

The muscle that assists the agonist is called the?

Synergist

20

Compare the roles of the three concentric layers of connective tissue wrappings in the organization of skeletal muscle

The 3 layers provide protection, sites for distribution of blood vessels & nerves, & a means of attachment to the skeleton

21

The endomysium electrically insulates each...

Muscle fiber. It has reticular fibers to help bind together neighboring muscle fibers & support capillaries

22

The perimysium contains extensive

Arrays of blood vessels & nerves that branch to supply each individual fascicle

23

The epimysium surrounds

The whole skeletal muscle

24

Describe the structure of tendons & their purpose in the body

Tendon structure: Thick, cordlike structure
Tendons purpose: Attaches the muscle to bone, skin or another muscle

25

Describe the structure of aponeuroses & their purpose in the body

Aponeuroses structure: Thin, flattened sheet
Purpose: Replaces a tendon in muscles that are flat and sheetlike & have a wide area of attachment

26

Ca++ bonds to troponin causing shift in

Tropomyosin

27

What is the structural & functional unit of the nervous system?

Neuron

28

Which two muscle tissues have striations?

Cardiac & skeletal

29

Skeletal muscle is derived from what tertiary development structure?

Myotome (somite is secondary structure)

30

What is rigor mortise?

Myosin heads don't let go of actin active site because of lack of ATP after death

31

How are muscle fibers & neurons similar?

-Both membranes can conduct action potentials
-Both show all-or-none response
-Both must reach a threshold level to trigger an action potential

32

-One neuron & all the muscle cells it contacts
-allows for fine & gross muscle control

Motor unit

33

Less cells per motor unit=

Fine control

34

Most fibers are

Fast or white

35

Slow fibers can sustain

Contraction; have myoglobin & extensive blood supply (aerobic); red in color=red fibers

36

Moderate endurance, red in color, aerobic, numbers depend upon exercise, fast fibers become intermediate fibers when used heavily

Intermediate fibers

37

Atrophy is

Loss of muscle mass, lack of use, loss of proteins, may result in cell loss, never regain those cells

38

Hypertrophy is

Exercise, increase in mass, not increase in fiber (cells), more myofibrils, more mitochondria, more blood supply, more glycogen

39

What is a motor unit?

One neuron & all the muscle fibers it stimulates

40

Why might atrophy be permanent?

Loss of cells, connective tissue buildup

41

* Fibers bundled at tracts
* Cell bodies in nucleus
* Myelin by oligodendrocytes

Central nervous system

42

Cell body off the side; sensory neurosn

Unipolar

43

A single dendrite & a single axon arising from opposite poles of the cell body

Bipolar

44

A nerve impulse is also called a

Action potential

45

Resting potential is

-70mv (millivolts)

46

Speed is affected by size of?

Fiber

47

Speed is affected by insulation of

Axons

48

Describe the difference between a nerve and a neuron

-Neuron refers to a single cell that has the ability to become "excited" & pass a nerve impulse along to a muscle, gland or another neuron
-Nerve refers to a structure made up of the fibers of many neurons. These fibers are bundled up in connective tissue. The fibers may be carrying impulses only toward the CNS, in which case it will be a sensory nerve.

49

Together the CNS & PNS perform 3 general functions

1) Collecting information
2) Processing & evaluating information
3) Responding to information

50

Responsible for input

Sensory nervous system

51

What are the functional divisions of the nervous system?

Sensory and motor nervous system

52

The sensory and motor nervous system breaks down further to

Sensory nervous system: Somatic sensory & Visceral sensory
Motor nervous system: Somatic motor & Autonomic motor

53

1) Contains receptors
2) Transmits information from receptors to the CNS

Sensory nervous system

54

1) Transmits information from CNS to the rest of the body
2) Sends motor information to effectors

Motor nervous system

55

The somatic sensory of the functional nervous system does what?

Receives sensory information from skin, fascia, joints, skeletal muscles, & special senses

56

The visceral sensory of the functional nervous system does what?

Receives sensory information from viscera

57

The somatic motor of the functional nervous system does what?

"Voluntary" nervous system: innervates skeletal muscle

58

The autonomic motor of the functional nervous system does what?

"Involuntary" nervous system: innervates cardiac muscle, smooth muscle, & glands

59

Define ganglion

gangli = a swelling) A group of neuron cell bodies.

60

What are the special senses?

Taste, vision, hearing, balance, & smell

61

Responsible for output?

Motor nervous system

62

The autonomic nervous system has two further subdivisions

Parasympathetic and sympathetic

63

What are the two distinct cell types that form the nervous tissue?

Neurons: Excitable cells that are able to generate, transmit, & receive nerve impulses
Glial cells: Nonexcitable cells that support & protect the neurons

64

This is sometimes called a nerve fiber

Axon

65

Axon terminals are

Also called telodendria which are an array of fine terminal extensions. The extreme tips of these have slightly expanded regions called synaptic knobs

66

The somewhat enlarged, often club-shaped endings by which axons make synaptic contacts with other nerve cells or with effector cells

Axon terminals

67

Myelin sheath

(myel = marrow) The fatty insulating substance around many axons.

68

Afferent neuron are

Also sensory neurons, that transmit nerve impulses FROM sensory receptors TO the CNS

69

Efferent neurons are

Also called Motor neurons, that transmit nerve impulses FROM the CNS TO muscles or glands

70

Describe the relationship and order of the sensory neurons, interneurons, & motor neurons

1) Sensory neurons carry afferent (input) signals to the central nervous system
2) Interneurons process info. in the CNS
3) Motor neurons transmit efferent (output) impulses from the CNS to effectors

71

How do neuroglia differ from neurons?

1) They are smaller and capable of mitosis
2) Glial cells do not transmit nerve impulses
3) Glial cells assist neurons with their functions

72

CSF is

Cerebrospinal fluid, a clear liquid that bathes the CNS & fills its internal cavities. Produced by the choroid plexus which is the ependymal cells & nearby blood capillaries that form a network.

73

The smallest percentage of CNS glial cells

Microglial

74

A collection of neuron cell bodies located outside the CNS

Ganglion

75

What is the main activity of axons?

Nerve impulse conduction

76

Action potential is

Also known as nerve impulse, a rapid movement of an electrical charge along a neuron's plasma membrane.

77

Why is nerve impulse also known as action potential?

Because a nerve impulse is caused by an actual voltage (potential) change that moves along the plasma membrane of the axon

78

The nerve impulse's ability to travel along an axon is affected by

A process called myelination

79

Define myelination

The process by which part of an axon is wrapped with a myelin sheath.

80

Neurilemma is

Sometimes used to describe the delicate, thin outer membrane of the neurolemmocyte when it myelinates

81

What are the two different myelinating glia cells

In the CNS, a myelin sheath forms from oligodendrocytes and in the PNS it forms from neurolemmocytes

82

What gives the axon a distinct, glossy white appearance?

The high lipid content of the myelin sheath

83

In the CNS, an oligodendrocyte can myelinate a portion of

Many axons

84

In the PNS, a neurolemmocyte can myelinate a portion of

A single axon only

85

Neurofibril nodes are

The small spaces that interrupt the myelin sheath between adjacent oligodendrocytes or neurolemmocytes. Also called nodes of Ranvier.

86

What happens at the neurofibril nodes?

At these nodes and only at these nodes can a change in voltage occur across the plasma membrane & result in the movement of a nerve impulse

87

Saltatory conduction is

The process in a myelinated axon, the nerve impulse jumps from neurofibril node to neurofibril node

88

Large diameter, myelinated axons conduct nerve impulses rapidly to the skeletal muscles in the limbs using

Saltatory conduction

89

Nerves are a component of the?

PNS

90

Sensory neurons convey sensory information to the

Central nervous system

91

Motor neurons convey motor impulses from the

Central nervous system to the muscles & glands

92

Mixed nerves convey

Both types (CNS & PNS) of information

93

Synapses are

Specialized junctions where axons terminate as they contact other neurons, muscle cells, or glands
where the nerve impulse is transmitted to the other cell

94

Synaptic knobs are

Swellings that are formed by the synaptic endings.

95

What do the synaptic knobs contain?

The synaptic knob is filled with membrane-enclosed vesicles containing a neurotransmitter

96

Synaptic cleft is

A very narrow space where the plasma membranes of the presynaptic neuron & postsynaptic neuron are separated. Separates the synaptic knob & motor end plate

97

Presynaptic neuron is

A neuron from the axon terminal of which an electrical impulse is transmitted across a synaptic cleft to the cell body or one or more dendrites of a postsynaptic neuron by the release of a chemical neurotransmitter

98

Post-synaptic neuron is

A neuron to the cell body or dendrite of which an electrical impulse is transmitted across a synaptic cleft by the release of a chemical neurotransmitter from the axon terminal of a presynaptic neuron

99

A neurotransmitter is

A signaling molecule. Most common is acetycholine (ACh)

100

The neurotransmitter is only released from the

Presynaptic cell

101

After the neurotransmitter is released what happens?

They then bind to receptor proteins found only in the plasma membrane of the postsynaptic cell, and this causes a brief voltage change across the membrane of the postsynaptic cell

102

Acetylcholine (ACh) is

The most common type of neurotransmitter. They cause a brief voltage change across the membrane of the postsynaptic cell

103

Synaptic vesicles are

Small secretory vesicles that contain a neurotransmitter, found inside an axon near the presynaptic membrane, and releases its contents into the synaptic cleft after fusing with the membrane

104

Neuromuscular junction

The point where a motor neuron meets a skeletal muscle fiber

105

Norepinephrine is

A neurotransmitter, norepinephrine relays brain impulses from one cell to the next and is involved in arousal, attention and mood.

106

Axon ending is

The somewhat enlarged, often club-shaped endings by which axons make synaptic contacts with other nerve cells or with effector cells. Also called end-feet, neuropodia, terminal boutons

107

Describe a chemical synapse

1) A nerve impulse travels through the axon & reaches its synaptic knob
2) The arrival of the nerve impulse at the synaptic knob causes an increase in calcium ion (Ca2+) movement into the synaptic knob through voltage-regulated calcium ion channels in the membrane
3) Entering calcium ions cause synaptic vesicles to move to & bind to the inside surface of the membrane; neurotransmitter molecules w/in the synaptic vesicles are released into the synaptic cleft by exocytosis
4) Neurotransmitter molecules diffuse across the synaptic cleft to the plasma membrane of the postsynaptic cell
5) Neurotransmitter molecules attach to specific protein receptors in the plasma membrane of the postsynaptic cell, causing ion gates to open
6) An influx of sodium ions (Na+) moves into the post synaptic cell through the open gate, affecting the charge across the membrane
7) Change in the postsynaptic cell voltage causes a nerve impulse to begin in the postsynaptic cell
8) The enzyme acetylcholinesterase (AChE) resides in the synaptic cleft & rapidly breaks down molecules of ACh that are released into the synaptic cleft. Thus AChE is need so that ACh will not continually stimulate the postsynaptic cell

108

True or false: Acetylcholine is actively transported from the pre-synaptic membrane to the post - synaptic membrane

False

109

True or false: If the post-synaptic membrane potential reaches threshold level, an action potential will be produced

True

110

What factors effect the speed of an impulse?

The axon's diameter & the presence (or absence) of a myelin sheath. The larger the diameter of the axon, the more rapidly the impulse in conducted because of less resistance to current flow as charged ions move into the axon. An axon with a myelin sheath conducts impulses many times faster than an unmyelinated axon because of the difference between saltatory & continuous conduction

111

Why do we have synapses?

1) They make sure that the flow of impulses is in one direction only. Because the vesicles containing the transmitter are only in the presynaptic membrane and the receptor molecules are only on the postsynaptic membrane
2) They allow integration
3) They allow ‘summation’ to occur
4) They allow the ‘filtering out’ of continual unnecessary or unimportant background stimuli
5) For communication